My husband also got sober around six to eight months after I left him. We attempted reconciliation. Thankfully, we did not move back into the same house together, since the reconciliation failed. The reason it failed is because, drinking or not, his behavior was not that of a partner. He was still selfish, immature, and pretty much incapable of being a husband and father. At least the kind of husband and father me and my kids needed.
Whether he's building up for a relapse or not is really immaterial. The question is whether or not he is working toward becoming a participating member of the family. If he is not, then he is a burden rather than an asset, regardless of his income.
Please try to separate your financial decisions from your relationship decisions. Staying with someone because you need his money is a sure way to lose yourself. And I second the suggestion to seek legal counsel. He is required by law to support his children whether you are married or not.
L